It is well known in the art of photographic science to add dyes to the structure of a photographic element in such a way as to absorb light from different regions of the electromagnetic spectrum. These dyes can be used to inhibit light from reaching a spectrally sensitized emulsion by a number of means including, but not limited to, being situated between the exposing source and the spectral sensitive emulsion. This method is typically employed in the art of color photography to ensure proper color balance as illustrated, for example, in Research Disclosure, No. 308, December 1989, Item 308119. Photographic elements are also known in which the filter dye is situated in such a manner as to absorb light which has passed through a spectrally sensitized emulsion layer. Exemplary examples of this application are presented when the dyes are used in underlayer or backing layer as illustrated, for example, in Research Disclosure, No. 308, December 1989, Item 308119. Photographic elements are also known in the art which utilize a filter dye, as exemplified by C-1, within the bounds of a photosensitive silver halide layer. Dyes within the bounds of the photosensitive absorb radiation which is scattered within the layer as well as radiation which exits the layer. The radiation which exits the emulsion is referred to in the art as print-through radiation. These prior art dyes are deficient due to the excessive loss of speed which occurs when the dyes are utilized within the bounds of the photographic layer. ##STR2##
The fundamental properties of any said filter dye include, but are not limited to, (a) an ability to wash out or bleach during processing to insure that residual color is not imparted to the final image and (b) photographic inactivity such that no adverse sensitometric effects are observed such as fog or desensitization.
Through diligent efforts a new class of diketo azo filter dyes have been discovered which have excellent photographic properties and can be utilized in any of the photographic structures currently known in the art.